The present invention relates to a solubilized cosmetic composition, more particularly it relates to a solubilized cosmetic composition which is superior in long term stability over time, is not accompanied by a sticky feeling in use, and is superior in clarity, without substantially containing a surfactant.
In the past, wide use has been made of cosmetic compositions which solubilize ingredients difficult to be dissolved in water, for example, perfumes, oil-soluble medicines, oils, and the like in the form of a cosmetic water, etc. It had been considered essential to formulate a surfactant into cosmetic compositions of a type solubilizing ingredients difficult to be dissolved in water so as to ensure stability over time of the cosmetics.
In recent years, however, greater safety has been expected even in cosmetic composition. From this viewpoint, the inclusion of surfactants in cosmetic compositions has been considered a problem in some cases. Therefore, it has been proposed to obtain a solubilized cosmetic composition, without substantially using a surfactant (for example, see JP-A-2-196709).
However, such a solubilized cosmetic substantially not containing a surfactant, is not sufficiently satisfactory in long term stability over time of the solubilized state. Further, in terms of usability, there had been a tendency for an accompanying sticky feeling of use.
Accordingly, an object of the present invention is to provide a solubilized cosmetic composition, which is superior in long term stability over time, and is not accompanied by a sticky feeling in use, substantially without using a surfactant.
In accordance with the present invention, there is provided a solubilized cosmetic composition containing an ingredient which is difficult to be dissolved in water, an alkyl-modified carboxyvinyl polymer and a hydroxyalkylated cyclodextrin so as to solubilize the ingredient difficult to be dissolved in water.
The present inventors engaged in repeated studies to solve the above-mentioned problems and found that by formulating an alkyl-modified carboxyvinyl polymer and hydroxyalkylated cyclodextrin in a cosmetic composition containing an ingredient difficult to be dissolved in water, the solubilized state was stabilized over a long period of time and the feeling in use was improved and, further, found that by formulating in a specific ratio of the ingredients, it was possible to obtain a solubilized cosmetic composition having a particularly superior clarity, whereby the present invention has been completed.
Note that, in this specification, unless otherwise indicated, xe2x80x9can ingredient which is difficult to be dissolved in waterxe2x80x9d will be referred to as xe2x80x9can ingredient difficult to be dissolved in waterxe2x80x9d. Further, a xe2x80x9ccosmetic composition obtained by solubilizing an ingredient insoluble in waterxe2x80x9d will be referred to as a xe2x80x9csolubilized cosmetic compositionxe2x80x9d, but the specific form is not questioned. Further, in the present specification, xe2x80x9csolubilizedxe2x80x9d means the ingredient difficult to be dissolved in water dissolves to at least the solubility in water and the turbidity of the aqueous solution is decreased. Further, in the present specification, xe2x80x9csubstantially not containing a surfactantxe2x80x9d means not containing a surfactant as a means for solubilizing the cosmetic and is not intended to positively inhibit the formulating of a surfactant in the cosmetic composition for other purposes.
The solubilized cosmetic composition according to the present invention is a solubilized cosmetic composition in which an alkyl-modified carboxyvinyl polymer and hydroxyalkylated cyclodextrin are formulated as solubilizing agents.
As the alkyl-modified carboxyvinyl polymer formulated in the solubilized cosmetic composition of the present invention, mainly an acrylate-methacrylate alkyl copolymer can be mentioned. The alkyl-modified carboxyvinyl polymer may be produced using a standard method according to the specific molecular structure. As the modifying alkyl group, a C10 to C20 alkyl group may be mentioned.
Further, a commercially available alkyl-modified carboxyvinyl polymer may also be formulated in the solubilized cosmetic composition of the present invention.
As such a commercially available product, it is possible, for example, to formulate, as an acrylate-methacrylate alkyl copolymer, Carbopol 1342, Pemulen TR-1, Pemulen TR-2 (each made by BF Goodrich), etc. into the solubilized cosmetic composition of the present invention.
The amount of the alkyl-modified carboxyvinyl polymer formulated into the solubilized cosmetic composition of the present invention is preferably at least 0.0001% by weight and not more than 1.0% by weight, based upon the total weight of the cosmetic composition. If considering the balance of the solubilizing power and usability, it is particularly preferable to formulate it in a range of at least 0.001% by weight to not more than 0.5% by weight, based upon the total weight of the cosmetic.
If the amount of the alkyl-modified carboxyvinyl polymer is less than 0.0001% by weight, the desired solubilization is not sufficiently achieved. Contrary to this, when the amount is more than 1.0% by weight, there is a strong tendency for an accompanying sticky feeling in use, and therefore, are not preferable.
Note that, when using a non-alkyl-modified carboxyvinyl polymer such those normally used as a thickener, for example, Carbopol 941 (made by BF Goodrich), Hiviswako 105 (made by Wako Pure Chemical Industries Ltd etc., the solubilizing power is weak and it is not possible to produce the desired solubilized cosmetic composition.
Further, the hydroxyalkylated cyclodextrin formulated in the solubilized cosmetic composition of the present invention (hereinafter sometimes abbreviated as xe2x80x9cHACDxe2x80x9d)is a cyclodextrin known in the past as a cyclic oligosaccharide (hereinafter sometimes abbreviated as xe2x80x9cCDxe2x80x9d)at whose hydroxy group a hydroxyalkyl group is introduced. That is, as the cyclodextrin, cyclodextrins having xcex1-, xcex2-, or xcex3-structures depending on the different number of glucoses (hereinafter sometimes abbreviated as xcex1-CD, xcex2-CD, and xcex3-CD) are known and commercially available. The hydroxyalkylated cyclodextrin formulated in the solubilized cosmetic composition of the present invention is produced by hydroxyalkylating the hydroxy group of these cyclodextrins. Note that, among the cyclodextrins serving as the base of these hydroxyalkylated cyclodextrins, normally xcex2-CD is used, but xcex1-CD or xcex3-CD may also be used as a mother nucleus. Further, it is possible to use an amylolyte containing all of these xcex1-CD, xcex2-CD, and xcex3-CD as a mother nucleus.
The replacement of the hydroxy group of the cyclodextrin with a hydroxyalkyl group may be performed using an ordinary known means (for example, see JP-A-2-196709). Further, the mole substitution degree of the hydroxyalkyl group is preferably 1 to 14.
As the hydroxyalkyl group replacing the hydroxy group, for example, substituent group such as a hydroxymethyl group, hydroxyethyl group, hydroxypropyl group, may be illustrated.
By the substitution reaction, it is possible to obtain hydroxyalkylated cyclodextrins such as hydroxymethylcyclodextrin, hydroxyethylcyclodextrin, hydroxypropylcyclodextrin, hydroxybutylcyclodextrin, dihydroxypropylcyclodextrin.
Further, among these hydroxyalkylated cyclodextrins, considering the production cost and easy production and the usability and the solubility in water of the cosmetic composition obtained by formulating the same into the solubilized cosmetic composition of the present invention, it is preferable to formulate a hydroxyethylated xcex2-CD or hydroxypropylated xcex2-CD in the solubilized cosmetic composition of the present invention. However, the hydroxalkylated cyclodextrin which can be formulated into the solubilized cosmetic composition of the present invention is not limited to these hydroxyalkylated cyclodextrins.
Further, these hydroxyalkylated cyclodextrins may be formulated into the solubilized cosmetic composition of the present invention alone, but mixtures thereof (mixtures suitably selected from hydroxyalkylated xcex1-, xcex2-, and xcex3-CD""s substituted by various types of hydroxyalkyl groups) may also be formulated.
The amount of the above hydroxyalkylated cyclodextrin formulated into the solubilized cosmetic composition of the present invention is preferably at least 0.001% by weight to less than 5.0% by weight based upon, particularly preferably 0.01% by weight to 1.0% by weight, the total weight of the cosmetic composition.
If the amount of the hydroxyalkylated cyclodextrin formulated is less than 0.001% by weight, the desired solubilization cannot be sufficiently performed, while conversely, if more than 5.0% by weight, not only is there a strong tendency for an accompanying sticky feeling in use, but also there is a tendency for a decreasing in the stability over time.
As a typical example of an ingredient difficult to be dissolved in water, formulated into the solubilized cosmetic composition of the present invention, a perfume or a fat-soluble medicine may be mentioned.
As the fat-soluble medicine, for example, vitamin A esters such as retinol, 3-dehydroretinol, retinal, 3-dehydroretinal, rhetinic acid, 3-dehydrorhetinic acid, vitamin A acetate, vitamin A palmitate, vitamin A such as xcex1-carotene, xcex2-carotene, xcex3-carotene, xcex2-cryptoxanthin, exinenon, and other carotenoids and xantophylls and other provitamins; vitamin D such as vitamin D2 to D7; vitamin E such as xcex1-tocopherol, xcex2-tocopherol, xcex3-tocopherol, xcex4-tocopherol, xcex1-tocotriel, xcex2-tocotriel, xcex3-tocotriel, xcex4-tocotriel, vitamin E acetate, vitamin E nicotinate, and other fat-soluble vitamins.
Further, as the fat-soluble medicines other than fat-soluble vitamins, Photosensitizing Dye No. 201, Photosensitizing Dye No. 301, stearyl glycyrrhetinate, glycyrrhetinic acid, xcex3-oryzanol, hinokitiol, musidine (phonetic), bisabolol, inositol, and the like may be mentioned.
These fat-soluble medicines and perfumes may, of course, be dissolved in the solubilized cosmetic composition of the present invention alone and may be dissolved in the case of any mixtures of two or more as well.
Further, the solubilized cosmetic composition of the present invention may further contain therein, in addition to the above-mentioned fat-soluble medicines, ingredients difficult to be dissolved in water generally formulated into cosmetics composition or pharmaceuticals to an extent not impairing the desired effect of the present invention.
Specifically, as an oil component, oils such as avocado oil, corn oil, olive oil, rapeseed oil, evening primrose oil, castor oil, sunflower oil, tea seed oil, rice bran oil, jojoba oil, cacao oil, palm oil, serge oil, lavender oil, squalane, squalene, tallow, Japan wax, beeswax, candelilla wax, carnauba wax, lanolin, silicone oil, fluorine oil, liquid paraffin, ceresin, vaseline, pentaerythritol ethylhexanoate, glyceryl ethylhexanoate, cetyl ethylhexanoate, glyceryl monooleate, may be mentioned. As a higher alcohol, capryl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, and the like may be mentioned. As a sterol, cholesterol, phytosterol, etc. may be mentioned. As a higher fatty acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, lanolin fatty acid, linoleic acid, linolenic acid, etc. may be mentioned. As UV absorbers, p-aminobenzoic acid, homomenthyl-7N-acetyl anthranilate, butylmethoxybenzoylmethane, glyceryl diparamethoxycinnamate-mono-2-ethylhexanoate, aminosalicylate, octylcinnamate, 2,4-dehydroxybenzophenone, oxybenzone, 4-tert-butyl-4xe2x80x2-methoxydibenzoylmethane, 2-ethylhexyl p-methoxycinnamate, sodium hydroxymethoxybenzophenone sulfonate, etc. may be mentioned. As an antibiotic preservative, p-oxybenzoate alkylester (ethylparaben, butylparaben, etc.), and hexachlorophene, etc. may be mentioned.
The amount of the ingredient difficult to be dissolved in water, formulated in the solubilized cosmetic composition of the present invention depends mainly on the amount of the alkyl-modified carboxyvinyl polymer. That is, the formulation of at least 10 times the above alkyl-modified carboxyvinyl polymer by weight with respect to the ingredient difficult to be dissolved in water is preferable in achieving the desired effect of the present invention.
That is, if the amount of the alkyl-modified carboxyvinyl polymer is more than 10 times the ingredient difficult to be dissolved in water, in particular the clarity of the solubilized cosmetic composition of the present invention is improved and superior effects are achieved in both the stability over time and stability immediately after preparation of the product.
The solubilized cosmetic composition of the present invention may contain therein, in addition to the water and the ingredient difficult to be dissolved in water, medicines and bases easily dissolvable in water which are generally formulated into cosmetics in the past to an extent not impairing the effect desired according to the present invention.
The form of the solubilized cosmetic composition of the present invention is not particularly limited so long as the cosmetic composition is one which requires solubilization of an ingredient insoluble in water by nature. For example, the present invention may be applied to a cosmetic water, tonic, clear gel, two-layer water-powder cosmetic, etc.